group. a federal magistrate the 19- year-old was advised of his miranda rights. there was more information in thele criminal complaint. ken wayne has been looking over it for us. >> reporter: this ten page criminal complaint lays out the fbi's case against tsarnaev. conspiring of using a weapon of mass destruction, a charge that if convicted could lead to the death penalty. dzhokhar tsarnaev is in serious conditions with gunshot wounds to the head, neck, leg, and hand. he has communicated to investigators by nodding and writing. at his bed side, a court representative says i will ask the doctor whether the patient is alert. the doctor asks, how you are feeling? tsarnaev nods. authorities are convinced the two brothers acted alone. >> i told boston they can rest easily. >> reporter: the affidavit describes the brothers walking through the marathon crowd with knapsacks and then separating. at one point, dzhokhar can be seen slipping his knapsack to the ground. he used his cell phone, then walked away. seconds later, an explosion. and information about a trip to russia last year.